Hygrometer sensor



FIG. 1 is a top plan view of a hygrometer sensor showing my new design;

FIG. 2 is a typical side elevational view thereof;

FIG. 3 is a front elevational view thereof, the rear view being a mirror image thereof;

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a hygrometer sensor, as shown and described. 